I want to clip a polygon shapefile by another polygon shapefile. Input polygon is the green one (first), clip polygon is the light blue one (second) and the result should look like the dark blue one (third). But the real result looks like the red one: there are some parts of the clip polygon which are missing (dark blue color under the red polygon). The projections are the same.
When I check the vector validity (Vector - Geometry Tools - Check geometry validity) for clip polygon, there appear 32 errors; probable cause of this wrong result.
I use QGIS version 2.14.2-Essen. What should I do to get the right result (dark blue one)?